kernel/trace/ftrace.c in the Linux kernel before 2.6.35.5, when debugfs is enabled, does not properly handle interaction between mutex possession and llseek operations, which allows local users to cause a denial of service (NULL pointer dereference and outage of all function tracing files) via an lseek call on a file descriptor associated with the set_ftrace_filter file.
git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=9c55cb12c1c172e2d51e85fbb5a4796ca86b77e7
lists.opensuse.org/opensuse-security-announce/2010-10/msg00003.html
lists.opensuse.org/opensuse-security-announce/2011-02/msg00000.html
secunia.com/advisories/42758
www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.35.5
www.redhat.com/support/errata/RHSA-2010-0842.html
www.securityfocus.com/bid/43684
www.ubuntu.com/usn/USN-1041-1
www.vupen.com/english/advisories/2011/0070
www.vupen.com/english/advisories/2011/0298
bugzilla.redhat.com/show_bug.cgi?id=631623